SU1097610A1 - Process for isolating dimethylformamide - Google Patents

Abstract

A METHOD FOR THE EXAMPLE OF DIMETHYL FORMATER FROM ELECTROLYTE, containing acid, by extraction of electrolyte with alkali and distillation 1 and the latter, characterized in that, in order to increase the purity and yield of dimethylformamide, the extraction is carried out successively in two stages: in the first stage, twice 40 - 46% with an aqueous solution of KOH at a volume ratio of electrolyte: KOH solution 2: 1-1: 1; in the second stage, solid KOH.

Description

from 1

A: The invention relates to an improved process for the separation of dimethylformamide (DMF) from mixtures, g / l DMF 800; boric acid 58.8; lemon acid acid 5.0; triethylamine 50.2; ethylene glycol 69.0; aniline 12.7; water 5.0 and can be used in various sectors of the industry for the disposal of industrial waste for the purpose of their repeated use in technological processes. A known method for the isolation of dimethyl formamide from a mixture containing formic acid, water and methylamine by distillation at atmospheric or reduced pressure in the presence of hexamethylenetetramine lj. There is also known a process for the introduction of dimethylformamide from a mixture containing formic acid and water by distillation in the presence of dimethylamine 2. However, the known methods do not provide a high quality yield of dimethylformamide from a mixture containing, g / l: boric acid 55.8; lemon 5; aniline 12.7; ethylene glycol 69; water 5; triethylamine 50.2, Isolation of dimethylformamide from mixtures by known methods is difficult due to decomposition of dimethylformamide catalyzed by acid and basic impurities, which does not allow obtaining the product of the required degree of purity. triethylamine in the ionized state. A high concentration of organic and inorganic salts increases the temperature of the method of boiling the mixture, which also decomposes dimethylformamide and contaminates it with high-boiling additives (ethylene glycol, aniline, triethylammonium salts), while the yield of dimethylformamide is 42%. Closest to the present invention, there is a method for separating dimethylformamide from a solution containing formic acid by treatment. solid alkali followed by distillation of the solution. The yield of DMF is almost quantitative. However, this method does not allow the selection of DMF with good quality and quality of electrolyte of the specified composition. The yield of DMF is 20%, the content of unidentified electrolyte decomposition products is 25 g / l, i.e. DMF does not comply with GOST 20289-74. The purpose of the invention is to improve the quality and yield of dimethylformamide. The goal is achieved according to the method, which consists in sequential extraction in two stages: in the first stage, twice with 40 - 46% aqueous solution of KOH at a volume ratio of electrolyte: solution of KOH 2: 1 - 1: 1, and in the second stage - solid KOH . Example. In a heat-resistant glass with a capacity of 2000 ml is poured 500 ml. electrolyte composition, g / l: DMF 800; boric acid 58.8; citric acid 5.0; triethylamine 50.2; ethylene glycol 69.0; aniline 12.7; water 5.0, 250 ml of a 46% aqueous solution of potassium hydroxide are gradually added and vigorously stirred for 5 minutes while cooling the mixture to 30 ° C. After stratification, the lower alkaline layer is separated, and another 250 are added to the upper organic ml of a 46% aqueous solution of potassium hydroxide and repeated extraction of boric and citric acid impurities. After separation of the mixture, two phases are formed. The lower phase contains a solution of potassium hydroxide, ethylene glycol, borate and potassium citrate; The upper phase contains dimethylformamide, triethylamine, aniline, ethylene glycol, and water. The upper phase is dried three times, adding solid potassium hydroxide in portions of 100 g. After drying from water, the upper phase is distilled. At 152-154 ° C, dimethylformamide is taken out, the yield of which is 69%, and the degree of purification corresponds to the qualification according to GOST 20289-74 (content of the main substance is 99.9%).

310976104

Experimental data on the yield and purity of DMF when it is obtained from electrolytes by known and proposed methods (electrolyte composition, g / l: DMF 800; boric acid 58.8; citric acid 5.0; triethylamine 50.2; ethylene glycol

69.0; aniline 12.7; water 5.0).

Table 1 .

Electrolyte treatment with di- 7.0 0.5 methylamine with a ratio of electrolyte: dimethylamine 5; 1 (molar ratio of acidic impurities: dimethylamine 1: 3) 2j

Double treatment with an electrolyte 0.05 No cleansing with 40–46% potassium narahydroxide solution itpK is the nominal electrolyte: KOH 2: 1–1: 1 ratio for 5 min, followed by drying the organic phase by treating it three times with solid KOH and distillation (proposed method)

A one-time treatment of 1.0– 0.3 electrolyte with a 40–46% potassium hydroxide solution at a volume ratio of electrolyte: KOH 2: 1–1: 1 solution for 5 min, followed by drying the organic phase by treating it three times with a solid con

Vtratnaya treatment of electrolyte 1,1,4 od 40-46% solution of potassium hydroxide at a volume ratio of electrolyte; Solution KOH 2: 1 and distillation.

10 20 g / l

69.0 12.7

unidentified

0.1

Not found

0.1

Not

Not

0.1

Treatment of the electrolyte with dimethylamine at an electrolyte: dimethylamine ratio of 5: 1 (molar ratio of acidic impurities: dimethyl amine 1: 3) 2 Double treatment of the electrolyte with 40-A6% potassium hydroxide solution at a volume ratio of electrolyte: KOH solutions 2: 1- 1: 1 for 5 minutes, followed by drying the organic phase by treating with solid KOH and distillation three times (proposed method)

Continued table. one

Continued table. 1 Does not comply with GOST 20289-74 99.0

98.3 94.0 100 100

98.1 92.0 100 100

96.4 92.0 100 100

100 98.0 60

99.8 Technical

Technical100 98.0 51 ches

90.2 20

Table 2 Data on DMF purification depending on the OL electrolyte volume ratio: 40–46% KOH solution DMF yield, Electrolyte volumetric ratio: AO-46%% KOH solution Table 3 Data on DMF purification depending on the concentration of the KOH extractant solution (electrolyte: KOH 2: 1: 1: 1 volume ratio) Output, DMF, KOH solution concentration, oil 10 10 Continued table. 3 As can be seen from the table. 1-3, the use of a set of technological methods in a specific sequence: extraction — treatment with potassium hydroxide — distillation makes it possible to increase the yield of dimethylformamide to 69% of the content in the electrolyte and improve its quality up to qualification according to GOST 20289-74.

Claims (1)

METHOD FOR ISOLATING DIMETHYLFORMAMIDE FROM ELECTROLYTE containing acid by extraction of an electrolyte with alkali and distillation of the latter, characterized in that, in order to increase the purity and yield of dimethylformamide, the extraction is carried out in two stages sequentially: in the first stage, twice with a 40 - 46% aqueous solution KOH with a volume ratio of electrolyte: KOH solution of 2: 1-1: 1, in the second stage - solid KOP. 1097610 1